MSD said a state law does not allow the sewer and flood protection agency to offer binding arbitration.

“Like many people, I am disturbed by the ad that was in The C-J on Sunday,” said Louisville Metro Councilwoman Attica Scott, D-1st District. “I cannot sit by when I hear workers complaining about racial discrimination.”

She asked MSD officials to provide a legal opinion on the matter.

MSD board President James Craig asked agency Executive Director Greg Heitzmanto do just that. Craig said MSD has offered something close to binding arbitration.

“We have offered arbitration that is more extensive than we ever (offered) before.”

Participants in the show of support included representatives of Laborers Local 576, AFSCME, Teamsters, AFL-CIO, Louisville Central Labor Council and Kentuckians For The Commonwealth.

The newspaper ad was paid for by Laborers Local 576, which has about 160 MSD employees, said the union’s attorney, Dave Suetholz. Without binding arbitration, terms of the contract cannot be enforced, he said.

The ad contrasted MSD workers in their Central Maintenance Facility with their counterparts at the Louisville Water Co. They claimed that the MSD workers were largely minorities, asserting their counterparts at the water company were largely not minorities — and that the MSD workers were paid less and have been working without a contract for two years.

The ad claims the MSD maintenance workers have not received a raise in three years.

MSD spokesman Steve Tedder said the agency has carried the provisions of the last contract forward, during negotiations. He also said the comparison in the ad was not fair because Louisville Water and MSD are two separate entities represented by different unions.

Tedder said he believed that union and management were scheduled go into mediation to resolve their differences in May.

MSD has two employee unions.

In September 2012, members of the National Association of Government Employees Local 189, which represents sewage treatment plant workers, agreed to accept a five-year contract.

The Courier-Journal reported at the same time that MSD workers who handle drainage, flood protection and sewer line maintenance had been members of another NAGE local, but voted to leave that union and join Laborers Local 576.

A union leader said then that employees were unsatisfied over help with dozens of pending grievances.

Reach reporter James Bruggers at (502) 582-4645 or on Twitter @jbruggers.